Malaysian Airlines MH370 contact lost
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Re post 5682: Oloberon said "surely these devices tell the holder where they are not possible searchers."
No, these devices broadcast the GPS-derived position to satellites and alert searchers to the location via text message etc.
Google "spot personal emergency locator beacon"
Many pilots own such things and carry them in whatever aircraft they may be flying.
Apologies, for some reason I can't actually quote in this forum, don't know why, so you'll have to scroll back to better see the context.
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No, these devices broadcast the GPS-derived position to satellites and alert searchers to the location via text message etc.
Google "spot personal emergency locator beacon"
Many pilots own such things and carry them in whatever aircraft they may be flying.
Apologies, for some reason I can't actually quote in this forum, don't know why, so you'll have to scroll back to better see the context.
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AIS data is notoriously unreliable. The AIS system is meant to prevent collisions between ships, and for that purpose it works well. There are a number of large multinational firms as well as government that subscribe to the AIS satellite and terrestrial coverage. There are two constellations of civilian satellites I am aware of that can pick up the AIS transmissions; there are probably more that are military/intelligence.
I worked extensively with a large AIS dataset for several years. We often times would see vessels with incorrect IMO numbers, duplicate vessels (in different positions) or even vessels located in the middle of Africa or Siberia. Part of this is due to how the transmissions arrive at the satellite; the transmissions can 'collide' and the satellite gets confused as to the true transmissions that are arriving simultaneously. This means that using the AIS data requires several layers of data cleansing.
Speed was notoriously unreliable on AIS and does not correspond with distance traveled for a vessel track. We would sometimes see vessels traveling at an indicated 100kt; obviously impossible. We would ignore speed and compute a vector based on the last two positions and elapsed time. Destination is also unreliable on AIS as it is entered by the crew and often times they will forget to change it after leaving a port.
Finally, AIS transmitters are deliberately turned off around the horn of Africa, mainly to avoid detection by pirates.
Spoofing an AIS signal would be trivial for anyone as well who wanted some type of 'civilian' cover.
I worked extensively with a large AIS dataset for several years. We often times would see vessels with incorrect IMO numbers, duplicate vessels (in different positions) or even vessels located in the middle of Africa or Siberia. Part of this is due to how the transmissions arrive at the satellite; the transmissions can 'collide' and the satellite gets confused as to the true transmissions that are arriving simultaneously. This means that using the AIS data requires several layers of data cleansing.
Speed was notoriously unreliable on AIS and does not correspond with distance traveled for a vessel track. We would sometimes see vessels traveling at an indicated 100kt; obviously impossible. We would ignore speed and compute a vector based on the last two positions and elapsed time. Destination is also unreliable on AIS as it is entered by the crew and often times they will forget to change it after leaving a port.
Finally, AIS transmitters are deliberately turned off around the horn of Africa, mainly to avoid detection by pirates.
Spoofing an AIS signal would be trivial for anyone as well who wanted some type of 'civilian' cover.
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In themselves, the previous pings tell us virtually nothing.
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Crew
To all who do not want to believe that the crew might be involved (and I can totally understand why, they are your peers): There are 200+ people on board, two of them we know are trained to fly a T7 - who would be your first suspect (albeit shouldn't be your only one)?
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In relation to those vessel tracker and marine traffic websites they work by volunteers feeding in the VHF AIS data frequency exactly like flight radar 24 so if there out of coverage of the nearest feeder it will only show the last position of the vessel when it had coverage.
I believe you can pay $300 a month to marine traffic and get the vessels position by satcom.
I believe you can pay $300 a month to marine traffic and get the vessels position by satcom.
There are sometimes errors in the AIS data and some aircraft and helicopters, particularly SAR ones, transmit AIS. These tend to only have a MMSI, i.e. no IMO.
Keeping Danny in Sandwiches
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I have doubt's about the crew, I really can't see anyone climbing 2000ft above max alt especially at the weight they were likely to be at. I suspect that the aircraft climbed at full power ran out of speed then dropped down to FL295 if that's what it did.
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commander who presumably often operated over the Indian Ocean he wanted to see what the approach patterns were for airfields that he might one day need to divert to? All the airfields that people are getting excited about are listed alternates for IOR ETOPS.
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Spoofing an AIS signal would be trivial for anyone as well who wanted some type of 'civilian' cover.
The Guys Who Can Make Oil Tankers Disappear, Virtually - ABC News
VHF ACARS (and possibly CPDLC) is similarly vulnerable from what I see.
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How confident are the authorities of the radar fix at 02:15 which has MH370 heading West? For me this fix and the two current search areas just don't match up. in my view either the 02:15 fix is wrong or they are searching in the wrong area?
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How confident are the authorities of the radar fix at 02:15 which has MH370 heading West? For me this fix and the two current search areas just don't match up. in my view either the 02:15 fix is wrong or they are searching in the wrong area?
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2) All or several pings measured the same distance to the aircraft. This would mean the aircraft was either stationary or flying exactly along the equi-distant radius to the satellite.
I accept however that the final two pings being the same distance from the satellite would strongly suggest a stationary aircraft and more coincident arcs than that would suggest the aircraft is on land and not in the process of sinking or drifting and therefore likely to be on the 'northern arc'. Those are the only conditions that I see the prior pings being of any help to the search.
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@twothree: Your explanation does not explain why the flight then continued via various waypoints...
Also there is perhaps a simple explanation why the search is south. Because the north end of the arc is not really accessable (politically) for a large scale search.
Also there is perhaps a simple explanation why the search is south. Because the north end of the arc is not really accessable (politically) for a large scale search.
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not B777 rated , but 0ver 10K hours on B737's, I have been thinking about this for a while.
I cannot help but still think its a catastrophic loss of electrical power, similar to to uncapping the battery switch and turning it off.......poof...instant darkness, no back up stby power....just total silence.
The engines will continue to work, being totally capable of suction feed only, as long as no large thrust changes are made.
The hydraulics will still operate as the hydraulic solenoids are only capable of being turned-off with electrical power, and without electrical power they are designed to default to open.
but Autopilot, autoflight systems, avionics, radios ACARS etc and vitally important pressurization will all fail.
If the crew were rendered unconscious thru this, the aircraft could well start a series of climbs and descends because the thin air at 35000ft is not conducive to aerodynamic stable flight.....but once it gets into thicker air at about 20000ft, the aerodynamic forces will allow the aircraft to reach a relatively stable flight regime, especially if the aircraft was in a cruise trimmed position at 35000ft.
the climb to 45000ft also makes sense w.r.t electrical failure......MACH TRIM......the aircraft has a tendency to tuck nose down at high cruise mach numbers, so the electrical mach trimmer applies some "nose-up trim" and then balances this with applied forward deflection of the control column........the loss of electrical power and the aircraft would release its forward control column input, hence the climb, into even thinner air, followed by phugoid action, as it would drop off at the top, eventually it would settle into an "in-trim" cruise at a much lower more dense atmosphere
Why the turn, I cannot explain
I cannot help but still think its a catastrophic loss of electrical power, similar to to uncapping the battery switch and turning it off.......poof...instant darkness, no back up stby power....just total silence.
The engines will continue to work, being totally capable of suction feed only, as long as no large thrust changes are made.
The hydraulics will still operate as the hydraulic solenoids are only capable of being turned-off with electrical power, and without electrical power they are designed to default to open.
but Autopilot, autoflight systems, avionics, radios ACARS etc and vitally important pressurization will all fail.
If the crew were rendered unconscious thru this, the aircraft could well start a series of climbs and descends because the thin air at 35000ft is not conducive to aerodynamic stable flight.....but once it gets into thicker air at about 20000ft, the aerodynamic forces will allow the aircraft to reach a relatively stable flight regime, especially if the aircraft was in a cruise trimmed position at 35000ft.
the climb to 45000ft also makes sense w.r.t electrical failure......MACH TRIM......the aircraft has a tendency to tuck nose down at high cruise mach numbers, so the electrical mach trimmer applies some "nose-up trim" and then balances this with applied forward deflection of the control column........the loss of electrical power and the aircraft would release its forward control column input, hence the climb, into even thinner air, followed by phugoid action, as it would drop off at the top, eventually it would settle into an "in-trim" cruise at a much lower more dense atmosphere
Why the turn, I cannot explain
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Getting the track from pings.
I clearly stated you would not get the heading
If the circles are relatively close together in time, it is flying north (or Sth, depending on the circles), if they are wide apart (or don't change) then it is flying E or W. Anything in between can be worked out with some assumption about cruise speed, possibly even without, I'll have to think about it.
[Not a great example, sort of assumes the satellite is sitting over the pole, which it isn't but it does not really change the viability. Also noted OldOberon post which I failed to credit and should have.]
Last edited by paull; 18th Mar 2014 at 17:44. Reason: My example assumes the satelite is at the Nth pole
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I understand all the wrinkles, but assuming constant heading and some assumption about cruise speed, you will actually get a track/position. (Actually 2 in most cases).
If the circles are relatively close together in time, it is flying north (or Sth, depending on the circles), if they are wide apart (or don't change) then it is flying E or W. Anything in between can be worked out with some assumption about cruise speed, possibly even without, I'll have to think about it.
If the circles are relatively close together in time, it is flying north (or Sth, depending on the circles), if they are wide apart (or don't change) then it is flying E or W. Anything in between can be worked out with some assumption about cruise speed, possibly even without, I'll have to think about it.
The fact that it has made someone think about it and get even more info from the scenario is good enough.
BTW i assumed constant speed because a) i think on auto pilot and b) references to cruise speed.